Articles are commonly monitored during manufacture and thereafter for inventory control purposes. A common practice in many fields is to apply a label to an article containing an identifier or other information associated with the article.
Regarding tire manufacture, to which the present invention finds particular application, identifying tires and other rubber-based articles can be problematic, particularly if the identification is to occur prior to fabrication and/or before production is complete. Tires and a wide array of other rubber-based articles can be subjected to one or more vulcanization processes in which the tire or tire components are fused or molded together. Vulcanization modifies the rubber-based composition by forming an extensive network of crosslinks within the rubber matrix, thereby significantly increasing the strength and durability of the article. Although numerous vulcanization techniques are known having various different curing systems, all or nearly all vulcanization techniques include the application of high pressure and elevated temperatures to the “green,” i.e., non-vulcanized, rubber-based article.
In view of these process conditions, adhesive-based labels have been developed that can be applied to green rubber-based articles such as tires, and which can endure the relatively high temperatures and pressures associated with vulcanization. While satisfactory in many respects, adhesive labels and adhesive bead labels are not designed to last the lifetime of the article and can become detached from the article due to the various types of stress the article is subjected to both during and after production.
Potential detachment of the label can be caused by label stiffness and the inability to handle the flexing of rubber during multiple stages of the tire build and when fitted on the rim. The problem starts initially during the vulcanization process while the mold is moving, and continues right after curing when the tire is still hot. If the tire is released from the mold and moves (e.g., flexes) too much, the label can fall off or at the least the adhesion is weakened as a result of the movement. Additionally, during the process of fitting the tire on a rim, the tire (particularly the bead area) is subjected to significant mechanical stress by the fitting machines. Lastly, when tires are in use, the various road and driving stresses can cause the bead label to detach from the tire.
Within the tire industry, label suppliers are concentrating on the development of better adhesives. Conversely, tire and rubber product producers are experimenting on the positioning of the label by applying the label in the so-called “non-flexing-zones” of the tire or rubber product. While these activities could potentially alleviate detachment to some degree, they are not final solutions. Additionally, the addition of RFID chips to current solutions contributes to detachment, and locating current labels behind the metal rim post-fitting impedes the ability to read the RFID chip from a useful distance.
Accordingly, what is needed is an alternative to an adhesive-based RFID label capable of remaining attached and operable to a rubber-based article during article production (e.g., vulcanization), distribution, inventory and article lifetime.